Linq表达树2

using System;
using System.Linq;
using System.Data.Linq;
using System.Data.Linq.Mapping;
using System.Linq.Expressions;
namespace KingRi.Test
{
    [Table(Name="account")]
    public class Account
    {
        [Column(Name="uname", DbType="varchar(50) NOT NULL")]
        public string Uname
        {
            get; 
            set;
        }
        [Column(Name="upass", DbType="varchar(50)")]
        public string Upass
        {
            get;
            set;
        }
    }
    public delegate void SelectDelegate<T1, T>(Account u);
    public class Client
    {
        static void Main()
        {
            DataContext ctx = new DataContext("server=.;database=t1;uid=sa;pwd=");
            Table<Account> users = ctx.GetTable<Account>();
            //IQueryable<Account> result = from u in users select u;
            IQueryable<string> result = users.Select<Account,string>(u=>u.Uname);
            /*
            ParameterExpression expression;
            IQueryable<Account> result = users.Select<Account,Account>(
                    Expression.Lambda<Func<Account,Account>>(
                        expression=Expression.Parameter(typeof(Account), "u"),
                        new ParameterExpression[] {expression}
                    )
                );
            */
            foreach(string a in result)
            {
                Console.WriteLine(a);
            }
        }
    }
}